Hyaluronic Acid
A large water-binding molecule the body already makes, used here as the highest-weight layer of a multi-weight system.
On the label: Hyaluronic Acid. Also known as HA, Hyaluronan.
What it does for you
Holds water at the surface, which is what gives skin an immediately plumper look.
Why we use it
Used alongside two smaller forms rather than alone. One molecular weight only works at one depth.
Mechanism
Hyaluronic acid binds many times its weight in water. At this size it stays at the surface and forms a hydrated film.
Commonly confused with
Hyaluronic acid, sodium hyaluronate and hydrolyzed hyaluronic acid are the same molecule at different sizes and in different forms, not three different ingredients.
What the studies say
Low molecular weight hyaluronic acid (20 to 300 kDa) passes through the stratum corneum, whereas high molecular weight hyaluronic acid (1000 to 1400 kDa) does not. This is the direct evidence that molecular weight determines the depth a given form reaches, and that the highest weight form stays at the surface rather than penetrating.
- Human skin, ex vivo analytical
Raman micro-imaging of transverse human skin sections to localise hyaluronic acid of three different molecular weights within the skin layers
Human skin penetration of hyaluronic acid of different molecular weights as probed by Raman spectroscopy Essendoubi M, Gobinet C, Reynaud R, Angiboust JF, Manfait M, Piot O. Skin Research and Technology, 2016. DOI 10.1111/srt.12228
An analytical localisation study, not a clinical outcome trial. It establishes where each size goes, not what each size achieves.
All five molecular weights significantly improved skin hydration and overall elasticity versus placebo. Wrinkle depth, however, improved significantly only in the 130 kDa and 50 kDa groups, which the authors attribute to better penetration of the lower weight forms. Read honestly, this supports using more than one weight, and it shows the higher weights carried the hydration result rather than the wrinkle result.
- Human in vivo (topical)
- n = 76 women aged 30 to 60 with periocular wrinkles
- 60 days
Randomized, vehicle-controlled; 0.1% hyaluronan at five molecular weights (50, 130, 300, 800 and 2000 kDa) applied twice daily to the periocular area, with a vehicle control cream around the other eye. Hydration, elasticity and wrinkle depth by semi-automated morphometry of negative replicas
Efficacy of cream-based novel formulations of hyaluronic acid of different molecular weights in anti-wrinkle treatment Pavicic T, Gauglitz GG, Lersch P, Schwach-Abdellaoui K, Malle B, Korting HC, et al.. Journal of Drugs in Dermatology, 2011
No DOI is registered for this paper, so the link points to its PubMed record. Several authors were affiliated with hyaluronan suppliers; check affiliations before treating it as independent.
Reviews hyaluronic acid and its derivatives in cosmetic formulation, and states that molecular weight influences both penetration into the skin and biological activity. Useful as the general reference for why a formula would use more than one weight rather than a single one.
- Review
Advantages of Hyaluronic Acid and Its Combination with Other Bioactive Ingredients in Cosmeceuticals Juncan AM, Moisa DG, Santini A, Morgovan C, Rus LL, Vonica-Tincu AL, et al.. Molecules, 2021. DOI 10.3390/molecules26154429
The authors declare no conflict of interest. A narrative review of formulation science, not a source of clinical effect sizes.